Adding Simple Dropdown to Checkout

Hi We need a simple dropdown with 6 variables in to a checkout of our clients The dropdown will be for shipping and add the price to the total, as follows UK FREE EU £1.95 Wordwide £2.65 UK Signed For £1.00 EU Signed For £7.95 Wordwide Signed For £7.95 They then can only checkout so far with google checkout or paypal. This is a wordpress website and the plugin which we are using for the simple shop on the clients website is called Simple Cart Buy Now ' [login to view URL] Please let us know if you need anything further Thanks